Newbie problem :)

In a particular worksheet I added a Command Button to execute the macro
below. When I click on the button the Excel "hour glass" appears and then
everything just "hangs", like it's in a loop or something.

If I execute the Macro below using Debug mode or just "Macro Run" from the
Excel toolbar it seems to work just fine.

I'm sure I'm doing something wrong that's very basic but being a newbie to
this stuff I don't know what it could be (I changed the row values while I'm
trying to figure out why it isn't working)?


Sub CommandButton1_Click()

'Turn screen updating and autocalculation off so it doesn't refresh for
every time a row is hidden
Application.Calculation = xlCalculationManual
Application.ScreenUpdating = False

'Perform loop starting in row 1004 and working "backwards" to row 7, one row
'at a time. For each row, if the value in the cell in column CK is 0, then
'hide the row.
For i = 30 To 7 Step -1
If Cells(i, "ck") = 0 Then Rows(i).Hidden = True
Next i

'Turn screen updating and autocalculation back on for normal operations
Application.Calculation = xlCalculationAutomatic
Application.ScreenUpdating = True

End Sub